Acidic fibroblast growth factor (aFGF), which influences the proliferation and differentiation of various cell types in vitro, were originally isolated as single chain proteins from neural tissue, including whole brain and hypothalamus. The aFGF is a heparin-dependent mitogen and it can strongly bind on all four known FGF receptors and their spliced form. It can be localized within specific subsets of neurons associated with motor and sensory functions, and can be purified from the adult brain. Purified aFGF is a mitogen for neuroblasts and promotes the neurites extension from spinal cord neurons.
Native peptide of human aFGF is isolated from human brain, and consists of 154 amino acids. However, 19 amino acids in N-terminal of the native human aFGF have been identified homogenous with human interleukin-1 (IL-1). The similar domain of polypeptide between human aFGF and IL-1 may cause the same endogenous immuno-response, including activation of macrophages, and modulated cells growth arrest (G. Venkataraman et al., P.N.A.S., 96:3658-63, 1999). Furthermore, the pro-inflammatory cytokine IL-1 and FGF-1 (aFGF)/FGF-2 (bFGF) share the same structural scaffold and compete against the same receptor binding site of tyrosine kinase domains (A. J. Minter et al., J. Cell Physil., 167:229-37, 1996).